Any discussion of the related art throughout this specification should in no way be considered as an admission that such art is widely known or forms part of the common general knowledge in the field.
Resistive change devices and arrays, often referred to as resistance RAMs by those skilled in the art, are well known in the semiconductor and electronics industry. Such devices and arrays, for example, include, but are not limited to, phase change memory, solid electrolyte memory, metal oxide resistance memory, and carbon nanotube memory such as NRAM™.
Resistive change devices and arrays store information by adjusting a resistive change element, typically comprising some material that can be adjusted between a number of non-volatile resistive states in response to some applied stimuli, within each individual array cell between two or more resistive states. For example, each resistive state within a resistive change element cell can correspond to a data value which can be programmed and read back by supporting circuitry within the device or array.
For example, a resistive change element might be arranged to switch between two resistive states: a high resistive state (which might correspond to a logic “0”) and a low resistive state (which might correspond to a logic “1”). In this way, a resistive change element can be used to store one binary digit (bit) of data.
Or, as another example, a resistive change element might be arranged to switch between four resistive states, so as to store two bits of data. Or a resistive change element might be arranged to switch between eight resistive states, so as to store four bits of data. Or a resistive change element might be arranged to switch between 2n resistive states, so as to store n bits of data.
Within the current state of the art, there is an increasing need to implement resistive change memory arrays into architectures compatible with existing technology. In this way, the advantages of resistive change memory can be realized in circuits and systems using conventional silicon based microprocessors, microcontrollers, FPGAs, and the like. For example, a number of circuit architectures (such as, but not limited to, those taught by the incorporated references) have been introduced that provide resistive change memory arrays and architectures that are compatible with existing non-volatile flash memory architectures. As the popularity and cost and design advantages of resistive change element memories increases, there is a growing need to provide higher speed and lower power circuit architectures for resistive change memory arrays to further increase the versatility of resistive change memory technology. To this end, it would be advantageous to provide a DDR compatible architecture for a resistive change element memory array.